Resources Flashcards
what resources do humans use
warm , shelter , food ,transport
how does agriculture help
helps to use the earth’s resources more efficiently
what is a finite resource
resources that cannot be replaced as quickly as being used up
what are examples of finite resources
- fossil fuels
- metals
- plastics
what are examples of renewable resources
wood
solar energy
hydropower
what does sustainability / sustainable development mean in terms of chemistry
meeting our needs without preventing future generations from meeting theirs
Give examples of natural resources and how they are used AND STATE the artifical alternative for each product
- wool - used for clothes and carpets, alternative synthetic product is acrylic fibre
- cotton - used for clothes, alternative synthetic product is polyester
- silk - used for clothes, alternative synthetic product is nylon
- rubber - used for tyres, alternative synthetic product is various synthetic polymers
- wood - used for construction, alternative synthetic product is PVC
what is potable water
water that is safe to drink
why is potable water not classified as pure water
because it contains dissolved substances.
what features should safe drinking water for humans have
drinking water should have sufficiently low levels of dissolved salts, and microbes
what source in the UK is our potable source
- rainwater - as it contains low levels of dissolved substances
where does rainwater collect
in the ground, lakes, and rivers = good sources of fresh water
what are the steps to produce good potable water
- choose a source of fresh water, such as a river ( the fresh water has low levels of dissolved minerals)
- pass the water through filter beds - this is to remove materials such as leaves, and suspended particles
- sterilise the water, to kill microbes
- in the uk, chlorine is used to sterilise the water
- other sterilising agents used ozone, and ultraviolet light
when is the process of desalinating water used
In countries where the main source of water is salty water = it contains high levels of dissolved substances
what does desalination do
reduces the levels of dissolved minerals down to an acceptable level for potable water
what are the ways to desalinate water
- by distillation
- by passing water through membranes, known as reverse osmosis
what is a disadvantage of distilation and reverse osmosis
very expensive as lots of energy is required
describe the required practical experiment to check for pure water
1) check the pH of the water - pure water has a pH of 7 (neutral)
2) this can be done by adding a small amount of the water to a universal indicator paper, which will turn green if the pH is 7
3) even if the pH is 7, the water still may not be pure, so testing for dissolved solids is now needed
4) use a balance to weigh an empty evaporating basin, and record the mass
5) fill basin with water, and place it onto a tripod and gauze, with a bunsen burner
6) use the bunsen burner to gently heat the water, until all water has evaporated, and allow the basin to cool
7) weight the evaporating basin again - if the mass increases, the water must have evaporated but left some crystals at the surface of the evaporating basin contained dissolved minerals = water was not pure
8) BUT IF THE MASS of the evaporating basin didnt increase = water didnt contain any dissolved solids = pure susbstance
describe the steps for the purifying water by distillation practical
- the apparatus has a conical flask, containing the water sample, on a tripod and gauze, with a delivery tube connected to the top of the flask, leading into a test tube, sitting in ice and water
1) gently heat the water, using a bunsen burner, so the water boils gently
2) the water will evaporate and form steam, and the vapour will travel along the delivery tube
3) when the water vapour enters the cold test tube, it will condense back into liquid water
- produced will be distilled water, which has no dissolved solids, and a pH of 7, meaning it is pure water
what must be done to sewage and agricultural waste before it is released into environment
require removal of organic matter, and harmful microbes, before being released into the environment
what are the steps required for treating wastewater
In the first stage, the sewage is screened by passing through mesh to remove large materials eg solids and grit
- the sewage then settles in sedimentation tanks, to produce sewage sludge, and liquid effluent
- The sludge is taken away into separate tank and digested by anaerobic bacteria ( by closing tank lid ) . In the absence of oxygen, the bacteria produce methane, which can be burnt for electricity
- the digested sludge can be used for fertilisers as it is rich in nutrients
- air is bubbled through the liquid effluent, to allow aerobic bacteria to multiply, and in the presence of oxygen the aerobic bacteria can digest the organic molecules, and harmful microorganisms
- after this, the liquid effluent can be safely discharged into rivers and seas
describe the ways that potable water can be produces but comment and the relative easiness for each method
using ground water from aquifers
- this is safe to drink, once it has been treated with chlorine
- however, aquifers can sometimes be polluted, so the water needs to be tested carefully
- potable water can also be produced directly from waste water, but this takes many purification steps, and so is only done in places where water is scarce
- salt water needs to be desalinated to produce potable water
- desalination requires lots of energy, and is expensive
what are the ways that copper can be extracted from ores
- by using sulfuric acid
- sulfuric acid is used to produce copper sulfate solution, before extracting the copper metal
- another way is smelting
- the copper ore is heated to a high temperature, in a furnace with air, to produce impure copper
- the impure copper is then used in electrolysis to make pure copper
- this requires lots of energy and electricity, and is expensive
now that copper is becoming scarce what are the ways to extract copper
from low-grade ores include phytomining, and bioleaching
what is an issue with low grade ores
are economically harder to extract than other ores
describe the process of phytomining
plants are grown on land, containing the metal compound
- these plants absorb the metal compound, and concentrate it in their tissue
- the plants are then harvested and burnt
- The ash contains a relatively high concentration of the metal compound
Describe the process of bioleaching
in bioleaching, bacteria are mixed with the low-grade ore
- the bacteria carry out chemical reactions, and produce leachate solutions
- the leachate contains the metal compound
how can metal compounds can be processed to obtain the metal
At the end of phytomining and bioleaching, the metal compound has been extracted, and now the metal needs to be extracted from the compound
- Copper can be obtained from copper compounds by displacement using iron- As iron is more reactive than copper, we use scrap iron as it is cheaper
Copper can also be extracted by electrolysis
what are advantages of bioleaching and phytomining
- allow us to economically extract metals from low - grade ores - important as earth’s resources of metal ores are becoming limited
- these metals don’t involve digging , transporting or disposing of large amounts of rock unlike traditional mining
describe the stages of the life cycle assessments
life cycle assessments are carried out to assess the environmental impact of products, in each of these stages:
- extracting and processing raw materials
- manufacturing and packaging
- use and operation during the product’s lifetime
- disposal at the end of its useful life
- this includes transport and distribution at each stage
what is the life cycle assessment for plastic bags
plastic bags are produced using chemicals from crude oil
- crude oil is a non-renewable resource
- extracting crude oil can be harmful to habitats, if there is an oil leak
- crude oil needs to be chemically processed, which requires a lot of energy, and releases waste products
- plastic shopping bags are strong, and are often reused
- at the end of the life, the bags have to be transported, either for recyling, or landfills
- plastic is non-biodegradeable, meaning it remains in the environment for a long time = they are a major form of litter, and fill up landfills
what is the life cycle assessment for paper bags
paper bags are made from wood, from trees
- wood is a renewable resource
- felling trees for wood is extremely destructive to forests
- wood needs to be chemically processed, which requires a lot of energy, and releases waste products
- making paper also requires lots of water
- paper bags are not very strong, and tend to tear, and therefore are often used only once, then thrown away
- paper bags are heavier than plastic bags, and can take more energy to transport
- paper breaks down quickly, and does not remain in the environment
what are issues with the LCA’s
- the use of water, energy, and production of some wastes, can be measured, and fairly easily quantified, however, we cannot always be certain how damaging they are to the environment
- allocating numerical values to pollutant effects is less straightforward, and requires estimates, or value judgement = these may not always be accurate
- life cycle assessments can also be biased, in support of claims for advertising purposes
What are examples of some materials that are produced from limited raw materials
Metals, glass, building materials, clay ceramics and most plastics
what harmful impacts does quarrying do
produces large amounts of dust and destroys habitats
what harmful impacts does mining do
releases harmful chemicals into the environment
what are the advantages and disadvantages of recycling
advantages : less acid rain , metal ore reserves last longer , conserved energy for mining saved , less mining, ,less landfill waste , landfill creates local employment
disadvantages : collection / transport problems , cost for transport , difficult to separate metals from appliances / other materials
how does recycling help reduce the use of resources
- it also helps us save limited resources and energy sources
- some products, such as glass bottles, can be reused
- glass bottles can also be crushed and melted, to make different glass products
- other products cannot be reused, and so are recycled for a different use
- plastic bottles can be recyled to make jackets and carpets
how can metals be recycled
- be recycled by melting, and recasting into different products
- one problem is that the amount of separation required for recycling depends on the material, and the properties required of the final product
- this reduces the amount of iron that needs to be extracted from iron ore, saving energy
what is corrosion
the destruction of materials by chemical reaction with substances in the environment
what is an example of corrosion
rusting
what metal is the only metal that rusts
- iron and alloys of iron eg steel
describe the rusting practical
place an iron nail in a boiling tube under three different test tubes, leave for several days, and observe whether or not it rusts
- the first test tube has distilled water, and is open to air (water and air)
- the second test tube has boiled distilled water, covered in oil, preventing air dissolving into the water (only water)
- the third test tube has anhydrous calcium chloride powder, which removes any water, and a rubber bung on top, preventing any moist air entering (only air)
- Now leave for several days and look for changes
what is the result for test tube 1 in the rusting practical
iron nail is covered in rust
what is the result for test tube 2 and 3 in the rusting practical
no rust
what are the conditions needed for rusting
water and air
what are the ways to stop corrosion
- using barriers between the environment and materials that we want to protect - THIS IS DONE USING GREASE OR PAINT
- electroplating and sacrificial protection
what is electroplating
electroplating is coating the material with a metal
Aluminium is used for this, as it naturally reacts with oxygen to form a thin layer of aluminium oxide = This protects the metal from further corrosion
what is sacrificial protection
- some coatings contain a more reactive metal, which acts as a barrier against air and water
- even if the coating is scratched, the more reactive metal will still react with air and water, and corrode, instead of iron
- an example is zinc, used to galvanise iron - the zinc acts as a barrier against air and water = prevents iron from corroding
what does galvanising mean
coating a metal with zinc
what is an alloy
a mixture, of metals blended with other elements
why are alloys harder than pure metals
because the atoms in an alloy are different sizes = distrupts the layers and stops them from sliding
give 2 examples of alloys of copper
bronze - alloy of copper and tin
brass- an alloy of copper and zinc
where is bronze used
statues - as bronze is hard and tends not to corrode
where is brass used
musical instruments and door handles - because even though brass is harder than normal copper, it can still be formed into different shapes
where is gold used
typically used for jewellery, but since pure gold is too soft , gold is alloyed with silver, copper and zinc to make harder
how is the purity of gold rated
in carats
how much pure gold is in 24 carats
100% pure gold
what is steel
alloys of iron-containing specific amounts of non- metal carbon and other metals
what is the properties of high carbon steel and where it is used
- extremely hard and brittle = easily tends to break
used to make cutting tools - eg chisel
what is the properties of low carbon steel and where it is used
- softer and more easily shaped
- used to make car bodies
what is an issue with steel and the prevention method
- as steel is an alloy of iron - it can easily rust
PREVENT: stainless steels used which contain chromium and nickel, making it hard, and resistant to corrosion
what are the properties of aluminium alloys
low density, making them useful to build airplanes
what is soda lime glass and how is it made
- most of the glass we use is soda-lime glass
- it is made by heating a mixture of sand, sodium carbonate, and limestone, until it melts
- when it cools, it can be solidified into any shape
what items ais soda lime glass ideal for
windows , bottles
what is a negative of soda lime glass
has a low melting point, limiting its uses
how is borosilicate glass made
by melting a mixture of sand and boron trioxide
what are the features of borosilicate glass
- higher melting point than soda lime glass
- useful for objects that require heating eg kitchenware and lab
ware
where are clay ceramics used and found
found : clay is a mineral found in the ground
uses: in pottery and bricks
how are clay ceramics made
by shaping wet clay, and then heating in a furnace to harden
how are most composites made
made by combining two different material
what is a key feature of composites
they have different properties to the materials in them
What is the reinforcement material in carbon fibre composite
the reinforcement material are fibres of carbon and the matrix is a plastic resin
what do the reinforcements contain
fibres or fragments of one material
- the reinforcement is then surrounded by a matrix or binder material
what are the properties of carbon fibre composite
- very strong and light = useful for cars or aircraft parts
what is reinforced concrete
- type of composite
- has steel bars surrounded by concrete
what are the properties of reinforced concrete
- extremely strong
- used to make buildings
how is a polymer formed
by joining together a large number of monomers
what do the properties of polymers depend on
- what monomers they are made from,
- the conditions under which they are made
what is low - density poly(ethene)
soft polymer
what types of poly(ethene) are made from ethene
low density
high density
what is the difference between low density and high density poly(ethene)
LD poly(ethene) is soft
HD poly(ethene) is harder
how can the property of a polymer be changed
the reaction temperature, reaction pressure, or the catalyst used could be changed
what type of polymers melt when we heat them
thermosoftening polymers - these can then be reshaped when they are soft BUT when cooled down they go back to a solid
what happens to the thermosoftening polymers when heated
-The intermolecular forces break and the polymer strands can separate from each other and the polymer melts
what happens to the thermosoftening polymers when cooled
- If we cool the melted polymer, we reform the intermolecular forces. The polymer goes back to a solid
do thermosetting polymers melt when heated
no
how are the polymer chains connected to eachother
by strong cross-links - these are not broken by heat which is why thermosetting polymers do not melt when heated
why do thermosetting polymers not melt when heated
Cross-links are not broken by heat which is why thermosetting polymers do not melt when heated
what is the equation for the Haber process
nitrogen + hydrogen —> <—-( iron catalyst ) ammonia
give an example of a use of ammonia
- to make nitrogen - based fertilisers for farming
what is the symbol equation for haber process
N2 ( g) + 3H2 (g) —–><—– 2NH3 (g)
what are the raw materials for the haber process
nitrogen and hydrogen
where is nitrogen extracted from
the air
how is hydrogen produced
by reacting methane with steam
describe the key stages of the haber process
- Purified nitrogen and hydrogen are passed over an iron catalyst around 450 degrees and 200 atmospheres pressure
- This causes some of the nitrogen and hydrogen molecules to react to form ammonia
- as the reaction is reversible - some of the ammonia breaks back down into nitrogen and hydrogen
- to increase the yield, the ammonia is cooled and turned into a liquid, which is removed
-the unreacted nitrogen and hydrogen can be recycles back over the catalyst
how can the temperature and pressure be adjusted to produce more ammonia
shift the position of the equilibrium towards the right hand side
in the haber process what is the forward reaction
exothermic - this means that a cool temperature will shift the equilibrium to the right side
what is the issue with the cool temperature shifting the equilibrium to the right side
- cool temperature makes the reaction slow - so there is a trade-off between the rate of reaction, and position of equilibrium
- if we increase the temperature, the rate of reaction will increase, but it will lower the yield
- 450°C is a compromise temperature, which gives a relatively fast rate of reaction, and a high yield of ammonia, using an iron catalyst also increases the rate of reaction
what is another way that equillibriuim is affected
by pressure - a high pressure will push the equilibrium to the right side
at what temperature is the percentage of ammonia its highest
at low temperatures - but at low temperatures it will reduce the rate of reaction
what happens to the rate of reaction and yield when the temperature is increased
- rate increases
- yield lowers
what does high temperatures require and what is needed as a result
lots of energy - so a compromise temperature of 450 degrees is used
at what pressure does the percentage of ammonia increase at
very high pressures
what is a disadvantage of working with very high pressures and how is it overcome
- extremely expensive
- dangerous
so we settle on a compromise pressure of 200 atmospheres
what is used to increase the rate of reaction
iron catalyst
why are fertilisers important for modern farming
as they replace the elements which have been taken up by the plant
what compounds do NPK fertilisers contain
compounds of nitrogen, phosphorus and potassium which improve agricultural productivity ( help plants to grow larger and more rapidly )
where are NPK fertilisers produced
large industrial facilities and a variety of different raw materials are processed together to produce the exact fertiliser
what are NPK fertilisers
formulations of different salts - the salts contain the required elements in the percentages needed by the plants
what is the main compound of nitrogen in NPK fertilisers and how is it made
ammonium nitrate ( NH4NO3)
how is the ammonium nitrate made
ammonia produced by haber process is used to produce nitric acid - the nitric acid is reacted with more ammonia to make ammonium nitrate
where does the potassium in NPK fertilisers come from
from the salts potassium chloride or potassium sulfate- both compounds are mined from the ground ( they can be used directly without further processing )
what is required for phosphate rock before being used in fertlisers
phosphate rocks has to be chemically processed
what are the products of treating phosphate rock with nitric acid?
produces phosphoric acid and calcium nitrate
what does phosphirc acid contain
contains phosphorus - but this cannot be added directly to plants - so this needs to be neutralised with ammonia = this produces ammonium phosphate which can be used in NPK fertilisers
What are the products of treating phosphate rock with sulfuric acid
a mixture of calcium phosphate and calcium sulfate - the mixture is called single superphosphate ( which can be used in NPK fertilisers )
What are the products for treating phosphate rock with phosphoric acid
produces triple superphosphate ( which can be found in NPK fertilisers )
describe the production of ammonium nitrate in the industry
- ammonia is used as a gas and nitric acid is concentrated = this is dangerous, as the reaction is exothermic, and releases a lot of heat, which is safely removed
- the heat is then used in later stages
- energy for evaporation is provided by the exothermic reaction
- ammonium nitrate is produced in a continuous process, meaning thousands of kilograms can be produced easily
describe the production of ammonium nitrate in the school/labs
in a school lab, dilute solutions of ammonia and nitric acid are used = this makes them safe to work with
- crystals are produced, using a water bath and bunsen burner = this requires a lot of heat energy
- in addition, only a small amount of ammonium nitrate can be produced in one go (known as a batch process)
